An archaic or dialectal past participle of 'crook,' meaning to bend or curve something; also possibly meaning to become crooked.
From crook as a verb, with the archaic -en suffix for past participles (seen also in 'broken,' 'stolen'), representing an older form of English that used -en more widely.
Crooken is almost extinct, but it shows English's historical -en endings—modern English has largely replaced these with -ed, so 'crooked' is now both the adjective and the past tense.
Complete word intelligence in one call. Free tier — 50 lookups/day.